6.012 - Microelectronic Devices and Circuits - Fall 2005Lecture 11-2Key questions•What is the topology of a small-signal equivalent cir-cuit model of the MOSFET?•What are the key dependencies of the leading modelelements in saturation?

6.012 - Microelectronic Devices and Circuits - Fall 2005Lecture 11-4Small-signal device modelingIn many applications, interested in response of device toasmall-signalapplied on top of bias:VGSVBSVDSID+idvgsvbsvds+-++--Key points:•Small-signal issmall⇒response of non-linear components becomes linear•Can separate response of MOSFET to bias and smallsignal.•Since response is linear,superpositioncan be used⇒eﬀects of diﬀerent small signals are independentfrom each other